By Ken Fry, PhD
The urban forest is a highly disturbed, albeit managed, ecosystem. Quite often the trees in an urban forest are isolated, planted in sub-optimal conditions, or subject to minimal maintenance. These conditions are considered to be highly disturbed in ecological terms. Compounding the stresses arising from these conditions is the risk of introduction of alien invasive species as a result of trade occurring on a global scale.
With increasing international trade, especially with partners in Asia and south Asia, comes the risk of alien invasive species becoming established in our urban forests. ‘Alien’ refers to any organism that originates from another ecoregion, although it is more commonly associated with organisms that originate from another continent. The term, ‘invasive,’ denotes the potential to become established in its new home, to be able to repeatedly overwinter successfully outdoors. Therefore, an alien invasive species is one that is not native and becomes naturalized, a permanent fixture in the local ecosystem. Often, this results in the displacement of native species that compete for the same resources or, in a worst case scenario, the over-exploitation of the resources due to the absence of any effective natural enemies.
Read the full article: Protecting The Urban Forest: Aliens, Biological Control, And Pests